1. Field of the Invention
The present invention relates to a spark plug for use in a combustion engine and more particularly, to an improved spark plug containing a U-shaped plate which moves in the up and down direction, caused by a compression stroke and an explosion stroke for cleaning up carbon deposited on a central electrode.
2. Description of Related Art
Various types of spark plugs for use in a combustion engine are known in the art. Generally speaking, as combustion is proceeding in a combustion engine, carbon generated therefrom is deposited on the grounding electrode.
As shown in FIG. 1, a conventional spark plug for use in a combustion engine includes a central electrode 3' and a ground electrode 8' for sparking a flame with a high voltage electric current from an ignition coil through the central electrode 3' to a compressed gas mixture in the combustion chamber. At this time, combusted gas generates carbon 10' which is deposited on the central electrode 3'. In such a conventional spark plug, the deposited carbon is removed by heating and maintaining the central electrode 3' at a high temperature of 450-950.degree. C.
However, in such a conventional spark plug the temperature of the central electrode 3' changes and cannot maintain the original temperature because of the driving situation of the combustion engine. Therefore, over time carbon 10 is deposited around the central electrode 3'. Accordingly, such a conventional spark plug cannot avoid the deposition of carbon on its surface.